Manufacturing and distribution facility managers use metrics to measure the productivity of a facility, and to determine what changes can be made to improve the operation of the facility. Metrics are used because it is difficult for any one person to otherwise understand how a large, complex system such as a manufacturing or distribution facility is performing. The choice of metric is important because changes that improve the facility as measured by the chosen metric are judged to be worthwhile and are encouraged by facility management. Changes that deplete the operation of the plant, as measured by the chosen metric, are judged to be detrimental to the operation of the facility, and are therefore discouraged by facility management.